I'm getting ready to replace both the engine and spark plug wiring harnesses on my M104 1993 300E 2.8. Phil did a great job in getting me the parts that I need, and I have some instructions but before I tackle it this weekend, what special tools or other parts (washers, seals, lube, etc) am I going to need that I can pick up beforehand?

You really don't need anything - maybe some basic tools. When you say "spark plug harness" do you mean spark plug wires (there's 3 of them)? I thought there was really only one harness.

where did you get your wiring harness and how much was it?

I got it from Phil, call him and he'll set you up with the right parts - I bought the spark plug wire set, 3 spark plug connectors and the engine wiring harness from him, saving over $200 when compared to the dealer.

The real saving will be with labour costs - my time is free, the dealer wanted over $1300 to replace these.

why is it that no one ever posts the price of this wiring harness. Do you have to be in some secret Mercedes cult to know the price? If so, where do I join? All I can ever find is "its around 500 at the dealership" but no one says for sure what the price is. You say you got it from Phil (at Fastlane I assume) so why don't they list it in their usual parts catalog? Are there any other 3rd party suppliers? This seems like a common enough replacement item that someone else should have one.

Part of the problem is that you need a ticker tape to know the price of MB parts these days - they go up so steadily. A wiring harness is essentially a dealer only item, some third parties sell them but they are getting them through MB and the prices are about the same as the dealer. All you can do is shop around. What people paid in the past isn't of much relevance.

I had partial sucess with the wiring harnesses yesterday. The engine wiring harness was fine - the old one had deteriorated to the point where a lot of the plastic connectors crumbled in my fingers as I tried to remove them.

The spark plug harness was different - when I tried to remove the ignitor coil on #2 cylinder, I noticed that the small screw in the corner was partially stripped, only half of the screw head was present and couldn't be turned (I was using the screwdriver that was in the car's toolkit, it was the only one I had that would fit).

My question is - how do I get that out? I can't turn it as it only has half the screw head - should I drill it out and replace the entire injector coil?

If any of you are needing to replace the wiring harness on your cars: Go out and do it immediatley - it's one of the easiest jobs you can tackle. Don't be put off by the cost of the harness, the labour is dead simple. Just lay the two harnesses by each other, and as you unplug the old, plug in the new. Dead easy.

You do not take that stud out .. it is simply a grounding stud for the coil mount
The coils just lift off the stud
The reason it is stripped is cuz the guy before you tried the same ..

If they're only there for grounding, why did the ignitor coils on cylinders 4 and 6 not come out until I had unscrewed the stud?

You did not have to take them out either
The coil pull straight up.. that's all.

If you look down the hole of a removed coil , you will see the grounding clip that slides on the stud as you remove/replace coils.

I tried pulling, it didn't move until the stud was unscrewed.

On the picture at http://img.eautopartscatalog.com/live/F300044431BOS.JPG it shows the nut on the underside of the coil that the stud screwed into - on mine there was a clip around it.

From what you're saying I take it that the nut and clip slid down over the stud - but why did the ignitor coil only pull off when the stud was unscrewed? the coil felt as though it was held down in the corner where the stud was.

You can attemp to remobe the stud , but it does not secure the coil and is as I mentioned
The reason we do not remove them is cuz they are brass/copper for conductivity and being such, they break at both the head and the base , requiring drilling the head out and re-tapping.
So, if you want to take tham off , feel free.
.the coils just get stuck, mostly from the boot sticking.. I always use dielectic when renewing for next time around.

http://www.peachparts.com/shopforum/showthread.php?t=64285&highlight=coil+stud

Can someone get rid of this guy..
He joined this morning and has already posted this crap on 14 different post..